1. Field of the Invention
The present invention relates to a grommet and a grommet checking apparatus. Particularly, the present invention is designed to accurately check whether or not a grommet of specified shape is mounted on a wiring harness.
2. Description of the Prior Art
When a wiring harness is mounted in a vehicle through a through hole formed in a panel of a vehicle body or the like, a grommet 1 of rubber shown in FIG. 13 is fitted in the through hole with the wiring harness inserted through the grommet 1 for waterproof, dustproof and soundproof purposes. The grommet 1 includes a vehicle body mount portion 1a having a tapered shape and a cylindrical wire insertion portion 1b continuous with a small diameter end of the vehicle body mount portion 1a.
The size and shape of the vehicle body mount portion 1a of the grommet 1 are set such that the mount portion 1a is fitted and held in the through hole of the vehicle body panel. No problem arises when a proper or specified grommet is mounted on the wiring harness. However, when an improper or nonspecified grommet is mounted on the wiring harness, the mount portion 1a cannot be fitted and held in the through hole of the vehicle body panel. If the mounted grommet is smaller than the proper grommet, waterproof performance and other performances are reduced. On the other hand, if the mounted grommet is larger than the proper grommet, it cannot be mounted on the vehicle body panel.
Accordingly, it is necessary to check whether or not a grommet of specified shape is mounted on the wiring harness. Checking has been conducted by the use of a checking device 2 as shown in FIGS. 14(A) and 14(B). The checking device 2 is formed with a recess acting as a grommet receptacle 2a. The shape of the grommet receptacle 2a differs depending upon the shape of the grommet 1. The grommet receptacle 2a includes a groove 2b in which the vehicle body mount portion 1a which is the lower half of the grommet 1 of specified shape is to be fitted, and a groove 2c in which the wire insertion portion 1b is to be fitted. A button 3 of a detection switch projects at the bottom surface of the groove 2b.
When the grommet 1 mounted with the wiring harness W/H is fitted in the grooves 2b, 2c of the receptacle 2a of the checking device 2 as shown in FIG. 15, a rim 1d of the vehicle body mount portion 1a of the grommet 1 presses the button 3 of the detection switch as shown in FIGS. 16(A) and 16(B). When a grommet 1 of nonspecified shape is fitted in the grooves 2b, 2c, the button 3 is not pressed, with the result that the mounting of the improperly shaped grommet on the wiring harness can be detected.
In the above checking device 2, as shown in FIGS. 17(A) and 17(B), even when a similarly shaped grommet 1' having a vehicle body mount portion 1a' whose diameter D is smaller than that of the vehicle body mount portion 1a of the specified grommet 1 is fitted in the groove 2b, the button 3 of the detection switch may be pressed upon contact of a rim 1d' of the vehicle body mount portion 1a' with the bottom surface of the groove 2b. Thus, the prior art checking device 2 may detect whether or not the grommet is mounted on the wiring harness, but cannot check whether or not the grommet 1 of specified shape is mounted.
In view of the above problem, an object of the invention is to provide a grommet and a grommet checking device for securely checking whether or not a grommet of specified shape is mounted on a wiring harness, including distinguishing amongst a plurality of kinds of grommets of different shapes, particularly having differently shaped vehicle body mount portions.